How Many Trimesters are in a Pregnancy?

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How Many Trimesters are in a Pregnancy?

First Trimester of Pregnancy: Weeks, Symptoms, Physical changes, Precautions, Clinical Tests, Diet Plan, Exercise, etc.


The first trimester of pregnancy is the initial phase of pregnancy. Fertilization, implantation, starting of embryonic development, these all things happen in the first trimester of pregnancy. This is the most critical phase of pregnancy, as most of the miscarriages occur in this phase.


Here we describe the first trimester by weeks, symptoms, precautions, required clinical tests, diet plans, exercise, etc.


Pregnancy Trimesters:


Pregnancy Trimesters

The 40 weeks of pregnancy divides into three phases, each phase called a trimester. So, there are three trimesters of pregnancy.

  • First trimester (from week 1 to end of week 12).

  • Second trimester (from week 13 to end of week 26)

  • Third trimester (from week 27 to end of the pregnancy).


First Trimester of Pregnancy Symptoms:

The best way to confirm pregnancy is to take a pregnancy test and ultrasound, but there are also some symptoms that signal us like missing the periods, morning sickness, fatigue and many more.


  • Spotting:

Soon after conception (from week 3 to week 4) the blastocyst attaches to the outer endometrial lining of the uterus. This process can cause spotting and this stays for less than three days. Sometimes, this may cause mild pain and cramping. According to a study with 4539 women, 28% of women are associated with spotting and light bleeding with pain.


  • Missing the Periods:

After the conception, your menstrual cycle stopped naturally. To maintain the pregnancy, the body produces human chorionic gonadotropin hormone. This hormone stops the ovaries from releasing mature eggs during the pregnancy, and that's why the menstrual cycle stops. Get a pregnancy test if you are likely to become pregnant after your period has stopped. If the result is positive, then see your doctor.


  • Swollen Breasts:

After conception, swollen breasts are a very common symptom to all. Because of hormonal changes in the body, women face this problem. After a few weeks, when the body adjusts with the hormonal changes, this discomfort will decrease.


  • Morning Sickness, Vomiting, Nausea:

At the first trimester of pregnancy, many women suffer from nausea and morning sickness. It can happen at any time of the day, the hormonal changes might cause it. Avoid an empty stomach and drink plenty of water. If the vomiting becomes severe, then contact your doctor.


  • Fatigue:

In the early stages of pregnancy the levels of progesterone increases which makes you feel sleepy.


  • Increased Heart Rate:

From week 8 to week 10 the heart pumps faster, as the heart pumps more and more blood at this time. So palpitations and arrhythmias are a common problem for all.


  • Mood Swings:

During the pregnancy, the hormonal imbalance can make mood swings. You feel more emotional and reactive as well. The mood swings also cause depression, anxiety and euphoria.


  • Increased Urination:

At this time, the amount of blood increases in your body that makes the kidneys to filter more liquid. As a result, it leads you to pee more.


  • Bloating and Constipation:

Because of hormonal imbalance at the early pregnancy, your digestive system becomes slow. It leads to constipation and bloating. Adding some fiber in your diet and drinking lots of water may help you.


  • High Blood Pressure:

In most of the cases, high or normal blood pressure is very common to all. But if the blood pressure increases severely, it may cause pregnancy difficulties. So strictly follow the dietary guidelines and have lots of water. Practicing some pregnancy-friendly exercises may help you a lot.


  • Heartburn:

Pregnancy hormones can cause the valve between stomach and esophagus to relax. It may allow the stomach acid to leak, and it causes heartburn. Eat small meals between every two hours instead of large one. Avoid oily foods, sit upright for at least an hour to allow more time to digest.


  • Food aversion and smell sensitivity:

At the time of pregnancy, your sense of taste may change, and you become more smell sensitive. In one review from National Institutes of Health reports from 1922 to 2014, the researcher found a trend that pregnant women rated odors as more intense during their first trimester.


  • Weight Gain:

It is the most common in pregnancy. At the end of the first trimester, you gain weight. You may gain 1-4 pound in the first few months. Week by week you gain more and more.


  • Pregnancy Glow:

The increased blood volume and hormonal changes make the oil glands of the body work more. As a result, the increased oil gives the skin a glossy appearance, which is called pregnancy glow. Some women also suffer from acne problems because of this.


Changes in body during first trimester of pregnancy by weeks:

During pregnancy, your body will go through many enormous changes. Here we mention your body changes during the first trimester by weeks.



  • Week 1 and 2:

In week 1 you are actually not pregnant to calculate the due date, doctors consider the last month period as the first week of pregnancy. In week 2 you are probably ovulating and this is the week of fertilization. This week, during intercourse, the male partner ejaculates semen in the female's vagina. Millions of sperms swim to reach the egg and one lucky swimmer first reaches the egg, and fertilizes it.



  • Week 3:

During week 3, the fertilized egg divides and makes a blastocyst. The blastocyst comes down towards the uterus from the fallopian tubes and attaches to the endometrial lining. This process is called implantation. During this, you may experience mild abdominal pain and light spotting, known as implantation bleeding. If the situation becomes severe, you bleed heavily, then contact your doctor immediately.



  • Week 4:

This week, you miss your regular periods. Take a pregnancy test and Congrats, your result is positive. From this week you felt the earliest signs of pregnancy like breast tenderness. Some women also start to feel fatigue, nausea, and bloating from this week.



  • Week 5:

From this week your baby develops some primary organs like neural tube, heart and blood vessels, and you develop mood swings. The hormonal changes make you more sensitive. Sometimes the mood swings can cause depression, anxiety and euphoria as well.



  • Week 6:

This week brings morning sickness. Although the name is morning sickness, it happens throughout the day. You feel nausea and vomiting, your sense of smell changes which brings food craving and aversions. Some women find relief by eating smaller meals and avoiding trigger foods.



  • Week 7:

From week 7, the human chorionic gonadotropin hormone increases the size of the uterus as the baby grows, and the kidneys filter more liquids than before. The increasing uterus creates pressure on the bladder, and more filtration makes you pee more frequently. So from this week plan your bathroom break more frequently.


  • Week 8 and week 9:

These weeks are full of morning sickness, mood swings, headaches, fatigue, breast tenderness. Additionally, these weeks bring digestion problems as well. Many women suffer from gas, bloating and constipation during this period. The hormonal imbalance makes the digestive system slow. You may have some relief by adding some fibers in your diet and drinking lots of water.



  • Week 10:

From this week your baby develops more frequently, and you also put on weight. Your belly and breast are getting bigger each week. The hormonal changes make your skin secrete more oils and as a result you have the radiant pregnancy glow on your face. Some women welcome acne problems with this also.


  • Week 11:

As your baby bump grows week by week, it may cause abdominal cramping.


  • Week 12:

This is the last week of the first trimester of pregnancy. At this phase the blood amount increases by about 50 percent during pregnancy. For this reason, you may have visible veins on your skin.


End of First Trimester:


End of First Trimester

The first trimester ends 3 months after the onset of pregnancy. At the end of the first trimester, all pregnancy symptoms come to the fore. The mother puts on weight and the baby develops all primary organs, also develops the sex organs. According to the Office on Women's Health, the baby is about 3 inches long and weighs almost 1 ounce at the end of the first trimester.



Precautions during first trimester of pregnancy:

A pregnant woman has to take several precautions during pregnancy. A slight mistake can put the baby and the mother in danger. Here we tried to give a list of what to follow during the first trimester of pregnancy. We clearly mention the dos and don'ts properly on this list.



  • Take multivitamin and mineral supplements:

Doctors recommend taking multivitamin and mineral supplements during pregnancy. This time, the expected mother required higher doses of certain nutrients, which are essential for baby's development and prevent birth defects. A mother needs prenatal vitamin doses like folic acid, iron and calcium etc. Vitamin rich green veggies also give you a good amount of nutrients from your regular diet.


  • Get vaccination:

Doctors recommend some vaccines to every pregnant woman at the early trimester. Mostly, they suggest influenza vaccine during flu season. If the woman gets vaccinated early, then at the time of childbirth there are no chances of getting infected by that.


  • Maintain a balanced and healthy diet:

Most times, the expected mother thinks that she should eat for two and this way she gains more and more weight, which causes difficulties during childbirth. Every pregnant woman should maintain a balanced and healthy diet throughout the pregnancy to stay fit. Breaking a large one into small meals and having them after every 2-3 hour is best for them. A normal weight woman should take 1800-2000 calories per day during the first trimester.



  • Stay hydrated:

A pregnant woman needs to stay hydrated at all times. At this time the blood volume increases, all the nutrients are going from your body to your baby through this water. So, you should always stay hydrated. About 8 to 10 glasses of water is essential for a pregnant woman during the first trimester.


  • Do workout:

Pregnancy workout is very beneficial for the expecting mother and for the baby too. Doing pregnancy friendly exercises, yoga or simple running and walking helps pregnant women to maintain the weight and the BMR as well. Daily exercise strengthens the muscles, increases flexibility which helps at the time of delivery. Regular exercise also prevents insomnia, muscle pains, mood problems, etc.


  • Have good sleep:

Every woman needs to get enough sleep during pregnancy. Because of various changes in the body, they need some rest at this time. A pregnant woman requires at least 8-10 hours of sleep during this time. Whenever you feel tired, take a nap and relax.


  • Have dental checkups:

Every pregnant woman should have regular dental checkups. The American College of Obstetricians and Gynecologists recommends that every expectant mother should have a routine oral health assessment.



  • Have regular sex:

The question that many have is whether it is safe to do regular intercourse after conception. Then the answer is yes, in normal pregnancy cases you can have intercourse during pregnancy until the water breaks. But if you have a complication factor such as placenta previa or another type of high-risk pregnancy then consult your doctor about it.




  • Avoid smoking:

We all know that smoking is very harmful to our body and in case of pregnancy smoking should be stopped before conceiving. Smoking during pregnancy directly harms the baby and causes birth defects. According to the National Institutes of Health babies born to women who smoke during pregnancy are more likely to have a lower birth weight and are at a greater risk for learning disabilities than children born to non-smoking mothers.



  • Alcohol and illegal drug consumption:

Alcohol and illegal drug consumption are strictly prohibited during pregnancy. People who consume alcohol during pregnancy deliver a baby with fetal alcohol syndrome (FAS). Studies show drug consumption during pregnancy causes miscarriages, premature birth, birth defects, etc. In many cases, the child is born drug dependent (neonatal abstinence syndrome).


  • Avoid hot tubs, electric blankets:

Relaxing in a hot tub, sauna or electric blanket during pregnancy is very dangerous for expecting mothers. According to American Journal of Epidemiology, using any of these during first trimester of pregnancy may double the risk of miscarriage and increase the risk of birth defects.


  • Avoid Kitty's litter box:

Probably you take care of your kitty always with your own hands but never clean the cat's litter box during pregnancy. Feline waste is full of many bacteria and parasites. Among them in particular a parasite, Toxoplasma gondii is very dangerous for a pregnant woman. Contract with this parasite causes many complications in your pregnancy, causes severe health problems of your baby even miscarriage, stillbirths can happen.


  • Avoid chemical exposure:

In daily life we ​​all are more or less exposed to chemical exposures. From pesticides to chemical fertilizers, chemical perfumes, air fresheners, everything contains more or less harmful chemicals. During pregnancy you need to avoid those chemical exposure as much as you can. There are some chemicals like lead, mercury, and arsenic which are very dangerous for women. These chemicals can harm your baby's health, cause miscarriages, still birth also. So you need to avoid these specifically.



  • Cut down caffeine:

Having excessive caffeine may harm the fetus of pregnant women so doctors suggest cutting down your daily caffeine consumption. During pregnancy less than 200 milligrams a day might be safe to consume.



  • Avoid seafoods having mercury:

Seafoods are generally rich in nutrients like omega-3 fatty acid, good for health but you must avoid seafoods which are high in mercury. The mercury can harm the baby's developing nervous system. The Food and Drug Administration (FDA) suggests avoiding seafoods like Bigeye tuna, King mackerel, Marlin, Orange roughy, Swordfish, Shark, Tilefish during pregnancy.


Avoid undercooked meat, poultry and eggs:

During pregnancy you must avoid undercooked meat, poultry and eggs because these increase the risk of bacterial food poisoning. If you are pregnant and food poisoning affects you it could harm your baby as well.



  • Avoid unpasteurised milk:

Every woman should intake dairy products during pregnancy as these products are full of calcium and vitamins but you have to be careful about where these products come from. Strictly avoid unpasteurized milk and milk products from consumption because these haven't been heated to kill bacteria. Consuming these products can cause illness and also harm the fetus very much.



  • First trimester clinical tests:

After conceiving, when you go to the clinic and consult your doctor, your doctor suggests some tests to find out if you and your baby have any kind of health problem. At the first visit, you have to do a blood test to confirm your pregnancy. After that your doctor asks for a blood test which will check the Rh factor of your blood, anemia, hepatitis B, STDs like HIV and syphilis, immunity to Rubella and Varicella, cystic fibrosis and spinal muscular atrophy. After that the doctor asks for some more tests depending on your age, medical history, etc.



  • First trimester screening test:

By this test they determine if the baby has any type of chromosomal abnormalities like down syndrome or trisomy 18. This test includes a blood test and an ultrasound test.



  • Ultrasound test:

During week 11 to week 14 you ask to do the ultrasound test to show the baby's shape and position.



  • Chorionic villus sampling (CVS):

Doctors recommend the chorionic villus sampling test between 10 to 13 weeks of pregnancy. This test is done with cells from the placenta to find out if the baby has any chromosomal abnormalities such as down syndrome.



  • Cell free DNA testing:

Those pregnant women who are at high risk of pregnancy ask to do this test. This test checks the fetal DNA in the mother's blood during week 10.

There are also many tests that your doctor can suggest to you after studying your health history, family health history, your age, etc.



  • First trimester diet plan:

Every expectant mother needs the right amount of nutrition during pregnancy. But food aversion, morning sickness makes it difficult for pregnant women to eat well. In some cases, expecting mothers don't know about the proper diet for them. So now we are going to give a little indication about the first trimester diet plan that may help you.



How many calories should a pregnant woman intake during the first trimester of pregnancy?

Since your baby is tiny, 1800 to 2000 calories per day is sufficient during the first trimester for a normal size woman.



What nutrients should a pregnant woman include in the diet plan during the first trimester?

The expectant mother should consume adequate amounts of nutrients for the development of the fetus during pregnancy. Here we are mentioning some essential nutrients during the first trimester.



  • Folic acid:

Folic acid or vitamin B9 is the most essential micronutrient for pregnant women. It prevents neural tube defects. A pregnant woman needs 600 micrograms of folic acid per day. To get the proper amount of folic acid, eat citrus fruits like oranges, strawberries, leafy vegetables, fortified cereals, cauliflower, dry fruits like nuts, etc.



  • Protein:

Protein is also very important during pregnancy as it helps in muscle development of the baby, helps in the mother's uterine development as well. A pregnant woman should have 75 grams of protein per day during the first trimester. Eat protein-rich foods like eggs, milk, chicken, sea foods, Greek yogurt, etc.



  • Calcium:

Calcium is essential for bone and teeth development of babies. The growing baby takes Calcium from the mother. Doctors recommend at least 1000 milligrams of calcium per day. Eat a good amount of milk, cheese, yogurt, leafy greens and vegetables to get proper nutrition.



  • Iron:

During pregnancy the blood volume increases about 50% in a pregnant woman. The key nutrient of blood hemoglobin is iron so a pregnant woman needs about 27 milligrams of iron per day. Eat beef, chicken, spinach, leafy greens to get proper nutrition and also ask your doctor for iron supplements.



  • Vitamin C:

A pregnant woman needs at least 85 milligrams of vitamin C during the first trimester. Eat citrus fruits like orange, lemon, strawberry to get the proper amount of this nutrient.


  • Potassium:

A pregnant woman needs 2900 milligrams of potassium per day during the first trimester. Eat banana, apricot, avocado and ask your doctor about supplements.



  • DHA:

DHA is the key omega-3 fatty acid which helps in brain development of babies. Eat low mercury sea foods to get this.



  • First Trimester Exercise:

Exercise keeps our body fit and fresh. If you are talking about pregnant women, then exercise is a must for them. According to the American College of Obstetricians and Gynecologists (ACOG) a woman who exercises during pregnancy regularly has a much lower chance of having a cesarean.


How much exercise should a pregnant woman do?

According to the Centers for Disease Control and Prevention (CDC) a pregnant woman should do at least 150 minutes of moderate intensity, low-impact exercise each week.


Benefits of exercise during pregnancy:


Benefits of exercise during pregnancy

According to the National Institutes of Health, exercise during pregnancy improves sleep, reduces stress and anxiety, reduces constipation and back pain, and improves ability to maintain a moderate weight during and after pregnancy.


Best exercises during first trimester of pregnancy:

  • Walking and jogging:

One of the most ideal exercises for pregnant women is walking and jogging on a flat surface. Walking is a low-impact exercise which can cause a moderate increase in heart rate. A pregnant woman can take 30 minutes of walking three to five times a week if they want.



  • Swimming and water aerobics:

Swimming and water aerobics are low-impact exercises which are very ideal for pregnant women during the first trimester of pregnancy. These exercises help to keep the body toned and strengthen the muscles. A pregnant woman can do 30 minutes of swimming or water aerobics sessions a few times per week during the first trimester.



  • Yoga:

A pregnant woman can practice pregnancy-friendly yoga. Yoga helps to stretch and strengthen the body. This yoga also teaches about calming down during labour, control breathing and meditation.



  • Kegel:

Kegel exercises prepare the expected mother for delivery. These exercises strengthen the pelvic muscles that support the abdominal organs, including the uterus, vagina, bowel, and bladder. Kegel exercises help to maintain the bladder function and reduce the risk of hemorrhoids.




We discuss the precautions of the first trimester, what to do and what to avoid.

After that we give some ideas about some clinical tests during this time. We give you an obvious idea about the first trimester diet plan and exercises. Hope this article is going to be helpful to you. You can also check out our previous articles about preconception care and about the development of a baby inside your womb.

Piyali Das

Piyali Das